The present invention pertains to a method and apparatus for making encoded master recordings of high-fidelity music to enable subsequent storage and retrieval by low-cost data processing techniques. More specifically, the invention relates to a system for storing encoded digital representations of sound recordings on a high-density storage media and for writing other indexing and/or indicia information associated with the program to enable accessing, playback and handling at high speeds.
A significant problem addressed hereby is retaining high sound fidelity in large volumes of digital representations for sound recordings. Unlike voice data handled by conventional telephone networks for low data transfer rates at user terminals, sound recordings of musical selections require substantial bit rates for real time transfers. Only complex and expensive digital data processing system can handle transfer rates required of conventional digital (e.g. 16-bit PCM) high-fidelity sound recordings, e.g., real time transfer rates of several hundred kilobytes per second and storage capacities of ten megabytes for each minute of high-fidelity music. Even greater demands must be met for high-speed transfers.
Attempts have been made to provide a practical store of concentrated digital representations of plural sound recordings (e.g., several thousand) which were immediately retrievable and reproducible, but current digital audio systems lack this capability. The well-known CD music ROM disks encoded by the conventional 16-bit PCM (pulse code modulated) technique hold some promise, but current off-the-shelf data processing systems are incompatible with them both in addressing algorithms and in transfer rate compatibility.
As an example, a juke box for retrieving and playing an audio program is known, but the information storage media have limited capacity using conventional formats. A practical system requires gigabytes of storage and data transfer rates of several magabytes/second in a form compatible with standard data processing equipment. A conventional desktop processing system has an effective data transfer rate of only 100 to 200 kbytes/seconds. PCM (pulse-code-modulation) encoded music, for example, requires a minimum data transfer rate of about 176 kbytes/second while faster-than-real-time recording, say eight times, would require a transfer rate of 2.8 megabytes/second. Sixteen-bit PCM encoded music requires about ten megabytes of storage for each minute of music. In light of these constraints, it is evident that present techniques provide neither high-speed transfers of re-recording, nor do they provide high volume archiving. Some prior systems including subject matter related to this invention are described in U.S. Pat. Nos. 4,528,643; 3,444,334; 4,4l0,917; 3,947,882; 3,718,906; 3,609,227; 4,355,338; and 3,311,378.
In view of the foregoing, it is a general objective of the present invention to provide a method and apparatus for storage and handling digital data representations of high-fidelity sound recordings by low-cost data processing techniques for high-density storage and/or high-speed transfer.
Another objective is to provide a method and apparatus for combining digital audio processing systems and techniques with low-cost digital data processing systems and techniques for handling audio program data.
It is a specific objective of the present invention to enable realization of a practical distribution and reproduction system for suitable for reproducing customized selections of audio programs of high fidelity at high speeds wherein the programs are reproduced on a slave recording medium directly from a high volume archive of master programs.
It is yet a further objective of the present invention to solve concerns of poor fidelity, deterioration of recording medium, limited selection of programs, inherent in many present-day storage media.
It is a further objective of the present invention to provide means that enable faster-than-real-time transfer of high-fidelity audio programs.
It is yet a further objective to provide a practical information store or archival system for premastering original master recordings in order to reduce the quantity of storage space required for a multitude of selections while at the same time enabling high-speed and high-fidelity reproduction thereof.
Another objective of the invention concerns developing a premastering system comprising time-domain condensed digital data signals representing audio programs which system enables storage of a large quantity of programs in a relatively small storage space.